I think this has to be from 1974 rather than 1972 as British airways were not formed until 1st April 1974 and their check in counter features in the film.
Great film and so many memories. Presumably a Super-8 mm film. It is later than 1972 though. The spectators terrace is on the roof of Terminal B (now Zone 2) which opened in 1975. Also visible are some Swissair DC-9-51 planes which were delivered to Swissair from 1975 onwards. So I would put the film as 1975 or later.